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Zhao M, Jiang H, Zhang S, Liu K, Zhou L, Wu D, Wen X, Hu J, Wang X, Liu Z, Sha Y, Zeng M. An unenhanced 3D-FLAIR sequence using long repetition time and constant flip angle to image endolymphatic hydrops. Eur Radiol 2024:10.1007/s00330-024-10906-1. [PMID: 38985183 DOI: 10.1007/s00330-024-10906-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 04/21/2024] [Accepted: 05/07/2024] [Indexed: 07/11/2024]
Abstract
OBJECTIVES To evaluate a three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequence using a long repetition time (TR) and constant flip angle (CFA) in differentiating between perilymph and endolymph in a phantom study, and unenhanced endolymphatic hydrops (EH) imaging in a patient study. METHODS Three solutions in similar ion and protein concentrations with endolymph, perilymph, and cerebrospinal fluid were prepared for variable flip angle (VFA) 3D-FLAIR (TR 10,000 ms) and CFA (120°) 3D-FLAIR using different TR (10,000, 16,000, and 20,000 ms). Fifty-two patients with probable or definite Meniere's disease received unenhanced CFA (120°) 3D-FLAIR using a long TR (20,000 ms) and 4-h-delay enhanced CFA (120°) 3D-FLAIR (TR 16,000 ms). Image quality, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of them were compared. Agreement in the evaluation of the EH degree between them was analyzed. RESULTS In the phantom study, CNRs between perilymphatic and endolymphatic samples of VFA 3D-FLAIR (TR 10,000 ms) and CFA 3D-FLAIR (TR 10,000, 16,000, and 20,000 ms) were 6.66 ± 1.30, 17.90 ± 2.76, 23.87 ± 3.09, and 28.22 ± 3.15 (p < 0.001). In patient study, average score (3.65 ± 0.48 vs. 4.19 ± 0.40), SNR (34.56 ± 9.80 vs. 51.40 ± 11.27), and CNR (30.66 ± 10.55 vs. 45.08 ± 12.27) of unenhanced 3D-FLAIR were lower than enhanced 3D-FLAIR (p < 0.001). Evaluations of the two sequences showed excellent agreement in the cochlear and vestibule (Kappa value: 0.898 and 0.909). CONCLUSIONS The CFA 3D-FLAIR sequence using a long TR could be used in unenhanced EH imaging with high accuracy. CLINICAL RELEVANCE STATEMENT Unenhanced imaging of endolymphatic hydrops is valuable in the diagnosis and follow-up of patients, especially those who cannot receive contrast-enhanced MRI. KEY POINTS Ion and protein concentration differences can be utilized in differentiating endolymph and perilymph on MRI. Endolymphatic and perilymphatic samples could be differentiated in vitro on this 3D-FLAIR sequence. This unenhanced 3D-FLAIR sequence is in excellent agreement with the enhanced constant flip angle 3D-FLAIR sequence.
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Affiliation(s)
- Menglong Zhao
- Department of Radiology, Zhongshan Hospital, Fudan University, and Shanghai Institute of Medical Imaging, Shanghai, 200032, China
| | - Huaili Jiang
- Otolaryngology Head and Neck Surgery, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Shujie Zhang
- Department of Radiology, Zhongshan Hospital, Fudan University, and Shanghai Institute of Medical Imaging, Shanghai, 200032, China
| | - Kai Liu
- Department of Radiology, Zhongshan Hospital, Fudan University, and Shanghai Institute of Medical Imaging, Shanghai, 200032, China
| | - Lei Zhou
- Otolaryngology Head and Neck Surgery, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Di Wu
- Department of Radiology, Zhongshan Hospital, Fudan University, and Shanghai Institute of Medical Imaging, Shanghai, 200032, China
| | - Xixi Wen
- United Imaging Healthcare, Shanghai, 201807, China
| | - Junpu Hu
- United Imaging Healthcare, Shanghai, 201807, China
| | - Xuan Wang
- United Imaging Healthcare, Shanghai, 201807, China
| | - Zhuang Liu
- Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China.
| | - Yan Sha
- Department of Radiology, Eye and ENT Hospital, Fudan University, Shanghai, 200031, China.
| | - Mengsu Zeng
- Department of Radiology, Zhongshan Hospital, Fudan University, and Shanghai Institute of Medical Imaging, Shanghai, 200032, China.
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Cheng Y, Han X, Xie W, Xu G, Bai X, Qi L, Zhang L, Liu R, Dong W, Feng W, Pang C, Zhang W, Liu F, Cao X, Xu Y, Luo G. Safety and efficacy of magnesium-rich artificial cerebrospinal fluid for subarachnoid hemorrhage. Front Neurol 2024; 15:1376216. [PMID: 38606277 PMCID: PMC11007082 DOI: 10.3389/fneur.2024.1376216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 03/19/2024] [Indexed: 04/13/2024] Open
Abstract
Objectives This study aimed to investigate the efficacy of using a newly formulated magnesium-rich artificial cerebrospinal fluid (MACSF) as an alternative to normal saline (NS) for intraoperative irrigation during aneurysm clipping in improving the prognosis of patients with Aneurysmal subarachnoid hemorrhage (aSAH). Methods Patients with aSAH who underwent intraoperative irrigation with MACSF or NS during the clipping in the First Affiliated Hospital of Xi 'an Jiaotong University from March 2019 to March 2022 were selected as MACSF group and NS group, respectively. The primary prognostic indicators were the incidence of favorable outcomes (mRS 0-2). The secondary outcome measures included cerebral vasospasm (CVS), mortality, total hospital stay, and intensive care unit (ICU) stay. Safety was evaluated based on the occurrence rates of hypermagnesemia, meningitis, and hydrocephalus. Results Overall, 34 and 37 patients were enrolled in the MACSF and NS groups, respectively. At 90 days after aSAH onset, the proportion of favorable prognosis in the MACSF group was significantly higher than that in the NS group (p = 0.035). The incidence of CVS within 14 days after surgery was significantly lower in the MACSF group than that in the NS group (p = 0.026). The mortality rate in the MACSF group was significantly lower than in the NS group (p = 0.048). The median lengths of hospital stay (p = 0.008) and ICU stay (p = 0.018) were significantly shorter in the MACSF group than in the NS group. No significant differences were observed in safety measures. Conclusion Using MACSF as an irrigation fluid for aneurysm clipping can significantly improve the 90-day prognosis of patients with aSAH, which may be related to the reduced incidence of CVS. Clinical trial registration https://www.clinicaltrials.gov, identifier NCT04358445.
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Affiliation(s)
- Yawen Cheng
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiangning Han
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Wanfu Xie
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Gaofeng Xu
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiaobin Bai
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Lei Qi
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Linjuan Zhang
- Department of Anesthesiology and Perioperative Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Rui Liu
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Weihua Dong
- Department of Pharmacy Intravenous Admixture Services, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Weiyi Feng
- Department of Pharmacy Intravenous Admixture Services, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Chengsen Pang
- Department of Pharmacy Intravenous Admixture Services, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Wei Zhang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Fude Liu
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiangqi Cao
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yue Xu
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Guogang Luo
- Department of Neurology and Stroke Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
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A biomimetic triple-layered biocomposite with effective multifunction for dura repair. Acta Biomater 2021; 130:248-267. [PMID: 34118449 DOI: 10.1016/j.actbio.2021.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 05/04/2021] [Accepted: 06/01/2021] [Indexed: 12/11/2022]
Abstract
Dura mater defect and subsequent cerebrospinal fluid (CSF) leakage usually appear in trauma or neurosurgical procedures and are followed by a series of serious complications and even death. The use of a qualified dura mater substitute with multifunction of leakage blockade, adhesion prevention, and dura reconstruction is one of the promising treatment methods. However, even though some products have been used in the clinic, none of the substitutes achieved the required multifunction. In this study, we aimed to design and fabricate a dura repair composite with the ideal multifunction. By biomimicking the structure and component of natural dura, we applied poly(L-lactic acid) (PLLA), chitosan (CS), gelatin, and acellular small intestinal submucosa (SIS) powders to successfully prepare a triple-layered composite. Then, a series of specific devices and techniques were developed to investigate the performance. The results revealed that satisfactory structural stability could be realized under good synergistic interactions among the components. In addition, all the findings suggested that the bionic triple-layered composite showed satisfactory multifunction of leakage blockade, adhesion prevention, antibacterial property, and dura reconstruction potential, and thus, it might be a promising candidate for dura repair. STATEMENT OF SIGNIFICANCE: Developing qualified dura mater substitutes with multifunction of leakage blockade, adhesion prevention, and dura reconstruction is crucial for treating dura mater defect and subsequent cerebrospinal fluid (CSF) leakage that appear in trauma or neurosurgical procedures. In this study, we designed and fabricated a triple-layered dura repair biocomposite with satisfactory structural stability and desired multifunction based on biomimicking of the structure and component of natural dura. Moreover, a series of specific devices and techniques were developed to investigate the relevant performance. Overall, the developed hydrogel electrospinning system exhibited excellent advantages in achieving multifunction and could be applied widely in the future to achieve multifunctional tissue repair materials.
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Cheng YW, Guo YC, Li GL, Deng YN, Li WJ, Xu GF, Deng Z, Cao YX, Luo GG. Effects of a new magnesium-rich artificial cerebrospinal fluid on contractile 5-hydroxytryptamine and endothelin receptors in rat cerebral arteries. Neurol Res 2019; 41:1015-1023. [PMID: 31559927 DOI: 10.1080/01616412.2019.1672383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Objectives Cerebral vasospasm after subarachnoid haemorrhage (SAH) is associated with cerebrovascular contractile receptor upregulation resulted from haemolysis in the subarachnoid space. This study developed a new magnesium-rich artificial cerebrospinal fluid (MACSF) formula and investigated its effects on receptor-mediated contraction in rat basilar arteries. Methods Clear and haemorrhagic cerebrospinal fluid (CSF) were collected from patients with hydrocephalus or SAH. MACSF was freshly prepared using clinical intravenous injections. Rat basilar arteries were segmented and incubated with clear CSF, haemorrhagic CSF or MACSF. The contractile responses were studied by myograph. The messenger ribonucleic acid (mRNA) and protein expression of 5-hydroxytryptamine 1B (5-HT1B), endothelin subtype B (ETB) and endothelin subtype A (ETA) receptors were evaluated by real-time polymerase chain reaction (PCR) and Western blot analyses. Results Haemorrhagic CSF exposure shifted the contractile curves induced by 5-hydroxytryptamine (5-HT), sarafotoxins 6c (S6c) and endothelin-1 (ET-1) leftward with increased maximal contraction values. Furthermore, mRNA and protein expression were markedly elevated for 5-HT1B, ETB and ETA receptors on arteries exposed to haemorrhagic CSF. However, the contractile responses to 5-HT, S6c or ET-1 and expression of 5-HT1B, ETB and ETA receptors in rat cerebral arteries exposed to MACSF remained unaffected compared to those exposed to clear CSF. Besides, unlike normal saline which can inactive in-vitro vessels, MACSF can maintain their physiological activity. Conclusion Haemorrhagic CSF induces upregulation of 5-HT1B, ETB and ETA receptors in rat cerebral arteries. However, MACSF can maintain in-vitro rat basilar arteries in good physiological activity and normal expression of contractile 5-HT and ET receptors.
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Affiliation(s)
- Ya-Wen Cheng
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
| | - Yi-Chen Guo
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
| | - Guo-Liang Li
- Department of Cardiovascular, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
| | - Yong-Ning Deng
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
| | - Wen-Juan Li
- Department of Neurology, Second Affiliated Hospital, Lanzhou University , Lanzhou , China
| | - Gao-Feng Xu
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
| | - Zhong Deng
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
| | - Yong-Xiao Cao
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center , Xi'an , China
| | - Guo-Gang Luo
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China
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Koizumi S, Hayasaka T, Goto-Inoue N, Doi K, Setou M, Namba H. Imaging mass spectrometry evaluation of the effects of various irrigation fluids in a rat model of postoperative cerebral edema. World Neurosurg 2011; 77:153-9. [PMID: 22099548 DOI: 10.1016/j.wneu.2011.03.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 01/12/2011] [Accepted: 03/29/2011] [Indexed: 12/14/2022]
Abstract
BACKGROUND Using imaging mass spectrometry (IMS), we investigated the cerebral protective effect of an artificial cerebrospinal fluid (CSF), ARTCEREB (Artcereb, Otsuka Pharmaceutical Factory, Inc., Tokushima, Japan), as an irrigation and perfusion solution for neurosurgical procedures in a rat craniotomy model. METHODS Wounds created in the rat cerebral cortex were continuously irrigated with Artcereb, normal saline, or lactated Ringer's solution at a steady rate for 4 hours, after which brain tissue was collected. Brain slices were prepared and analyzed using IMS. RESULTS In tissue surrounding the injury, the signal intensity for Na adduct ions to phosphatidylcholine was high and that for K adduct ions to phosphatidylcholine was low. This is thought to reflect the level of water retention in brain cells and to be a change accompanying edema. The signal intensity with Na adduct ions to phosphatidylcholine was significantly lower in the Artcereb group than in the physiological saline or lactated Ringer's solution groups. CONCLUSIONS IMS analysis in a rat craniotomy model indicated that the level of water retention in brain cells, calculated from the signal intensity of Na-adducted phosphatidylcholine around the wound area, was lowest in the Artcereb group, suggesting that artificial CSF that has similar composition and properties to human CSF can minimize edema in the brain surrounding the surgical wound.
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Affiliation(s)
- Shinichiro Koizumi
- Department of Neurosurgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Possible detrimental effects of neurosurgical irrigation fluids on neural tissue: an evidence based analysis of various irrigants used in contemporary neurosurgical practice. Int J Surg 2010; 8:586-90. [PMID: 20673818 DOI: 10.1016/j.ijsu.2010.07.292] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/03/2010] [Accepted: 07/21/2010] [Indexed: 11/21/2022]
Abstract
Physiological saline and other solutions used as irrigation fluids during neurosurgical procedures have long been debated to cause adverse effects on neural tissue. Laboratory based research over the past fifty years has described the possible harm caused to central nervous system cells by normal saline, and has advocated the use of safer alternatives such as lactated Ringer's solution and artificial cerebrospinal fluid. However, there is a dearth of corresponding clinical studies to support this standpoint. Worldwide, normal saline remains the most widely used neurosurgical irrigation fluid. We have attempted to document the preference of practicing neurosurgeons worldwide regarding the irrigation fluids via an electronic mail survey, and have analyzed the available evidence on the relative safety of various irrigation fluids. We recommend the use of lactated Ringer's solution and artificial cerebrospinal fluid as neurosurgical irrigants, especially during neuroendoscopy and longer procedures requiring application of copious amount of irrigation fluid.
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Fujita Y, Doi K, Harada D, Kamikawa S. Modulation of physiological hemostasis by irrigation solution: comparison of various irrigation solutions using a mouse brain surface bleeding model. J Neurosurg 2010; 112:824-8. [DOI: 10.3171/2009.7.jns09561] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Intraoperative bleeding often obscures the surgical field and may cause neurological damage. The irrigation fluids used during surgery might affect physiological hemostasis because they modulate the extracellular fluid composition of the bleeding area directly. The authors therefore investigated the influence of irrigation fluid on hemostasis in a mouse brain surface bleeding model.
Methods
The cerebral cortices of ddY strain mice were exposed under irrigation with normal saline, lactated Ringer (LR) solution, or artificial CSF (ACF-95). To investigate the influence of electrolytes, calcium, potassium, or both were also added to the saline. After 10 minutes of irrigation at 100 ml/hour, sequential photographs of the surgical area were taken with a microscope, and the number of bleeding points was counted visually. Irrigation and counting were performed in a masked manner.
Results
There were significantly more bleeding points after irrigation with normal saline than with ACF-95; LR solution had a similar effect on physiological hemostasis as ACF-95. Saline augmented with calcium or potassium and calcium was superior to normal saline in terms of hemostasis.
Conclusions
The authors demonstrated that the irrigation fluid used in neurosurgery affects bleeding at the surgical site. To avoid surgical site bleeding, ACF-95 and LR solution should be used as irrigation fluids instead of normal saline. The calcium and potassium content of irrigation solutions seems to be important in hemostasis.
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Affiliation(s)
- Yasutaka Fujita
- 1Research and Development Center, Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima; and
| | - Kazuhisa Doi
- 1Research and Development Center, Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima; and
| | - Daisuke Harada
- 1Research and Development Center, Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima; and
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Kazim SF, Enam SA. Re: various irrigation fluids affect postoperative brain edema and cellular damage during experimental neurosurgery in rats (Doi et al. Surg Neurol. 2006;66:565-72). SURGICAL NEUROLOGY 2007; 68:118; author reply 118-9. [PMID: 17586251 DOI: 10.1016/j.surneu.2007.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
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Doi K, Kawano T, Morioka Y, Fujita Y, Nishimura M. Various irrigation fluids affect postoperative brain edema and cellular damage during experimental neurosurgery in rats. ACTA ACUST UNITED AC 2006; 66:565-71; discussion 571-2. [PMID: 17145310 DOI: 10.1016/j.surneu.2006.06.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 06/26/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND This study was conducted to investigate how various irrigation fluids used during neurosurgical procedures affect the degree of postoperative brain edema and cellular damage during experimental neurosurgery in rats. METHODS The cerebral cortex was exposed and incised crosswise with a surgical knife under irrigation with an artificial CSF, lactated Ringer's solution, or normal saline. Four hours after injury, irrigation was stopped and brain tissue samples were obtained from injured and uninjured sites. Specific gravity, cerebrovascular permeability, and TTC staining of the samples were evaluated. Incision and irrigation of the brain were not performed on the control group. RESULTS At the injured site, specific gravities of the samples in the normal saline group and the lactated Ringer's solution group were significantly lower than the specific gravity in the artificial CSF group. The EB concentration was significantly higher in the lactated Ringer's solution group and relatively high in the normal saline group as compared with the artificial CSF group. TTC staining did not differ significantly between the artificial CSF group and the control group. It was significantly lower in the lactated Ringer's solution group and the normal saline group than in the control group and the artificial CSF group. CONCLUSIONS As compared with normal saline and lactated Ringer's solution, artificial CSF reduced postoperative brain edema, cerebrovascular permeability, and cellular damage in sites injured by experimental neurosurgery in rats.
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Affiliation(s)
- Kazuhisa Doi
- Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory, Inc, Tokushima 772-8601, Japan.
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Kandimalla KK, Donovan MD. Transport of hydroxyzine and triprolidine across bovine olfactory mucosa: role of passive diffusion in the direct nose-to-brain uptake of small molecules. Int J Pharm 2006; 302:133-44. [PMID: 16105724 DOI: 10.1016/j.ijpharm.2005.06.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 06/22/2005] [Accepted: 06/22/2005] [Indexed: 10/25/2022]
Abstract
Hydroxyzine and triprolidine have both been reported to reach the CNS following nasal administration. The objective of this study was to investigate their in vitro permeation across bovine olfactory mucosa in order to further characterize the biological and physicochemical parameters that influence direct nose-to-brain transport. In vitro experiments were conducted using Sweetana-Grass (Navicyte) vertical diffusion cells to evaluate the effect of directionality, donor concentration and pH on the permeation of hydroxyzine and triprolidine across excised bovine olfactory mucosa. These studies demonstrated that the Jm-s (mucosal-submucosal flux) and Js-m (submucosal-mucosal flux) of hydroxyzine and triprolidine across the olfactory mucosa were linearly dependent upon the donor concentration without any evidence of saturable transport. Hydroxyzine inhibited the efflux of P-gp substrates like etoposide and chlorpheniramine across the olfactory mucosa. Both hydroxyzine and triprolidine reduced the net flux (Js-m-Jm-s) of etoposide with IC50 values of 39.2 and 130.6 microM, respectively. The lipophilicty of these compounds, coupled with their ability to inhibit P-gp, enable them to freely permeate across the olfactory mucosa. Despite the presence of a number of protective barriers such as efflux transporters and metabolizing enzymes in the olfactory system, lipophilic compounds such as hydroxyzine and triprolidine can access the CNS primarily by passive diffusion when administered via the nasal cavity.
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